Abstracts

Rationale: We describe the case of one patient at Boston Children’s Hospital, a 5-year-old with remote right hemispheric strokes and medically refractory left hemiclonic seizures, who underwent right functional hemispherectomy in 2019 using MR-guided laser induced thermal therapy (LITT), highlighting a novel application of this surgical approach. This is the first use of LITT for functional hemisphectomy, to our knowledge. LITT is a minimally invasive surgical approach that has typically been used for selective ablation of epileptogenic brain lesions in epilepsy patients, although it has the potential to be used in other scenarios that require focal resection or disconnection.The LITT approach was chosen in this case to minimize the risk of bleeding, large fluid shifts, hypotension, and sepsis associated with an open functional hemispherectomy given the patient’s multiple medical co-morbidities, including congenital heart disease (transposition of the great arteries and VSD requiring multiple previous cardiac surgeries) as well as end stage IV renal disease pending renal transplant. Completion of an open procedure after transplant with improved kidney function could mitigate some the hemodynamic risks but would introduce the risk of operating with chronic immunosuppression. Pre-operative planning included a multidisciplinary team meeting between members of the epilepsy surgery team (epileptologists, neurosurgeons) and the patient’s cardiologist, nephrologist, and anesthesiologist to discuss and optimize the surgical approach and intra-operative safety. Methods: During surgery, five laser compatible electrodes were implanted with robotic assistance, three along the corpus callosum (one anterior, one posterior, one along the superior margin) and two in the right temporal region (one lateral, one medial); an external ventricular drain was also placed to measure intra-operative intracranial pressure. The patient underwent laser ablation at 4-6 sites along each electrode track. There was essentially minimal blood loss and no significant hemodynamic instability during the procedure. Results: The patient tolerated the procedure well, with a >90% reduction in seizure burden at last follow up. In the immediate post-operative period, the patient did experience transient increases in intracranial pressure and accompanying vomiting, requiring delayed removal of the external ventricular drain and a course of steroids; ultimately these symptoms resolved completely and the drain was removed. The patient has experienced an anticipated post-operative worsening of a baseline left hemiparesis but remains ambulatory with however at a recent follow up, gains ingains in speech production. Conclusions: This case demonstrates that in select cases, LITT functional hemispherectomy may be a safe and effective alternative approach to an open procedure. Features of the current case that made LITT an attractive option included easy access to the corpus callosum afforded by the large area of cystic encephalomalacia in the area of remote stroke, as well as the multiple medical co-morbidities that created significant risks to made an open procedure relatively risky. Future studies are needed to adequately assess the safety and effectiveness of this approach. Funding: No funding